Signal9 CTF Archive
Seasonal, hands-on Linux capture-the-flag — forensics, incident response, and hardening on real systems. Past seasons ship with full write-ups.
Play the current season →July Season: Ghost in the Machine
Three compromised boxes, three flags buried in the aftermath. Hunt the persistence, read the logs, and recover what the intruder left behind — all on sandboxes you fully control. Defensive practice only.